Criado method

So, Equation (21.12) is used to plot the master Z(a) versus a curves for the different models hsted in Table 21.3, whereas Equation (21.13) is used to represent the experimental curve. The activation energy values in Equation (21.13) are usually obtained through the FWO method [38, 39]. The Criado method uses reference theoretical ctnves obtained from Equation (21.12) that are derivatives of the (a) and a) functions represented in Table 21.3 (called master curves) which are compared to experimental data for determination of the mechanism of a solid-state process [35,42]. These mechanisms represent how the sohd-state degradation process occurs. The algebraic expressions that represent the theoretical mechanisms are separated into four main groups, and F, as can be seen in Table 21.3. These mechanisms describe the... 

Figure 21.12 Master curves and experimental data obtained using the Criado method for EUG (a) and curaua (b).

Criado and Ortega(140) concluded that Reich and Stivala s method makes possible the assignment of an n order to a reaction that follows quite a different mechanism. In such a case, the method gives erroneous values of E. 

Many other mathematical methods have been proposed to analyze non-isothermal kinetic data to determine unequivocally the exact kinetic model using functional forms of < (a) or /(a) of the rate-controlling step (154). Criado (155) found that it was impossible in the Coats and Redfern method to distinguish between an interface chemical reaction-controlled mechanism (R3) and the Jander diffusion mechanism (D3). Bagchi and Sen (156) also demonstrated the inadequacy of the Coats and Redfern method in identifying unambiguously the rate-controlling mechanism of the dehydroxylation of Mg(OH)2. 

Real C, Alcala MD, Criado JM (2004) Synthesis of silicon nitride from carbothermal reduction of rice husk by the constant-rate-thermal-analysis (CRTA) method. J Am Ceram Soc 87 75-78... 

Percentages of the crystal phases present were determined from integrated XRD peak heights according to the method of Criado et.al [10). Additionally, the formation of pseudo-brookitc is apparent in specimens of greater than 2 atom% nominal iron content calcined at 1073K. Evidence of pseudo brookite is also obtained in the specimen TF/SP/10/973. 

---